I fully agree with you that "macroevolution" and "microevolution" come
from the literature of evolutionary biology and paleontology. The
problem is that the same words are used differently, and in a muddled
fashion, by anti-evolution creationists. In particular, when
paleontologists talk about "macroevolutionary trends," they are
obviously referring to more than genetic processes. There are also
unique events which have had great determinations on our evolutionary
history, such as impacts by large comets or asteroids. Or, for example,
if our sun went into a cycle of average decreased energy output such
that the earth's average temperature dropped significantly, this would
have obvious effects on life on the earth, and this would be reflected
in our evolutionary history (the fossil record). It is no surprise that
paleontologists focus on such things.

It is these kinds of considerations that make macroevolution much more
than the sum of the biological processes involved in microevolution, and
why you can't extrapolate microevolutionary processes to determine or
explain macroevolutionary trends.

Creationists have made hay over misconstruing these kinds of
terminological distinctions for a few decades now, but that hay was full
of weeds when they gathered it to begin with, and by now it's been in
the barn so long it's very old, moldy, and rotten, and the cattle and
horses just won't eat it.

So when you state that "the distinction between micro- and
macroevolution was formulated by evolutionary biologists (not
creationists or design theorists), and remains a topic of active
research and debate within evolutionary theory," this is, of course,
correct. Creationists just aren't using these terms in the same way.

And this is all beside the primary point, which is that there is nothing
other than the "microevolutionary" processes involved in genetic
inheritance in a species population, and interactions with other species
in an ecosystem, that has been yet found to be needed to account for
evolutionary change. Species evolution is the only evolution that there
is. That this can't explain a particular historical event and that
event's effect on macroevolutionary trends, such as a massive extinction
event by a large asteroid impact (which is explained by astronomy and
geology and not biology) which produces radical changes in the
"evolutionary landscape," is completely irrelevant to the
anti-evolutionist argument.

>> What is it about "macroevolution," what are the
>> characteristics of this evolution that are the cause
>> for raising some kind of distinction from
>>"microevolution"? Is this a distinctive kind
>> of evolution recognized through scientific
>> observation? Or is this concept something in
>> the eye of the creationist beholder?
>
> Somebody, I think on this list, once remarked that
> "microevolution" is usually effectively defined as
> "evolution I believe in" while "macroevolution" means
> "evolution I don't believe in." I too would like to
> see anti-evolutionists give the terms scientific
> definitions and use them consistently. I'm not
> holding my breath.

The terms "microevolution" and "macroevolution" were
coined by Russian evolutionary geneticists in the late
1920s, and were already common parlance in the
evolutionary literature by the mid 1930s. See, for
instance, the introduction to Dobzhansky's _Genetics
and the Origin of Species_, where he describes the
"reluctant sign of equality" that biologists have placed
between micro- and macroevolution:

"...there is no way toward an understanding of the
mechanisms of macro-evolutionary changes, which
require time on a geological scale, other than through
a full comprehension of the microevolutionary processes
observable within the span of a human lifetime and
often controlled by man's will. For this reason we
are compelled at the present level of knowledge
reluctantly to put a sign of equality between the
mechanisms of macro- and micro-evolution, and,
preceeding on this assumption, to push our investigations
as far ahead as this working hypothesis will permit."

A "working hypothesis" can fail under contrary evidence,
of course, and today many evolutionary theorists argue
that there is in fact an inequality between micro- and macro-
evolution. See, for instance, this recent paper by
paleontologist Douglas Erwin:

SUMMARY [Erwin's abstract]: Arguments over macroevolution versus
microevolution have waxed and waned through most of the twentieth
century. Initially, paleontologists and other evolutionary biologists
advanced a variety of non-Darwinian evolutionary processes as
explanations for patterns found in the fossil record, emphasizing
macroevolution as a source of morphological novelty. Later,
paleontologists, from Simpson to Gould, Stanley, and others,
accepted the primacy of natural selection but argued that rapid
speciation produced a discontinuity between micro- and
macroevolution. This second phase emphasizes the sorting of
innovations between species. Other discontinuities appear in
the persistence of trends (differential success of species within
clades), including species sorting, in the differential success of
clades and in the origination and establishment of evolutionary
novelties. These discontinuities impose a hierarchical structure to
evolution and discredit any smooth extrapolation from allelic
substitution to large-scale evolutionary patterns. Recent
developments in comparative developmental biology suggest
a need to reconsider the possibility that some macroevolutionary
discontinuities may be associated with the origination of
evolutionary innovation. The attractiveness of macroevolution
reflects the exhaustive documentation of large-scale patterns
which reveal a richness to evolution unexplained by microevolution.
If the goal of evolutionary biology is to understand the history of
life, rather than simply document experimental analysis of evolution,
studies from paleontology, phylogenetics, developmental biology,
and other fields demand the deeper view provided by macroevolution.

[end abstract]

In short, the distinction between micro- and macroevolution was
formulated by evolutionary biologists (not creationists or design
theorists), and remains a topic of active research and debate
within evolutionary theory.